Material for killing insects



. Io Drawing.

Patented Jan. 20, 1 931 T I UNITED; STATES PATENT; orrlca BUBIC 0. 30m AND RICHARD T. COTTON, OF WASHINGTON, DISTRICT OF COLUMBIA, ASBIGNOBS TO THE GOVERNMENT AND THE PEOPLE OF THE UNITED STATES OI AMERICA HTML FOR KILLING INSECT Application fled lovember 8'8, 182?. Serial Ho. 285,888,

(GBAI'I'ED man. THE ACT 02 MABGE 8, 1883, A8 ENDED APRIL 80, 1928; 870 0. G. 75

This application is made under the act of March 3, 1883, chapter 143 (22 Statutes 625) j and the invention herein describe an claimed may-be used by the Government of I gating grain weevils in box cars and bins;

clothes moths, carpet beetles, and furniture beetles in iumigating vaults; and stored product insects in general.

Another object is to provide a material for :tumigating weevils in grain which will not injuriously afiect the milling properties or? the grain, the baking qualities of the flour made therefrom, or the value as feed-studs oi the grain or of the bran and other hy products resulting in the manufacture of the flour. At the present time carbon disulfide is en tensively employed for destroying weevils and other injurious insects infesting wheat and other grains,-but certain ver serious disadvantages attend the use of t is material Its odor is offensive and the vapor in moderate concentration is quite toxic to man. While quite volatile, complaints. occasionally come from millers that wheat which has been treated with carbon disulfide still carries its odor, and it has been proven that the bahng leading railway systems in the quality of fiour from carbon disulfide fumigated wheat is sometimes injuriously1 afi'ected.

The most serious objection to t e use of carbon disulfide as a fumigant however, arises from the fact that it is readily inflammable and that its vapor whenmixed with air is highly explosive. For this reason fire insurance companies refuse to carry the fire risk on elevatorsduring such time as carbon disulfide is being used to treat the grain contained therein. Recently the General Managers Association of Chicago, re resenting the nited States adopted a resolution prohibiting the use of carbon disulfide for fumigating cars of grain.

There is, therefore, a great need of asubstinever come into commercial use.

tute for carbon disulfide for fumigating purposes.

A great variety of substances otherthan carbon disulfide have been'proposed and tried in the fumigation of grain weevils, but have Some of these substances are: carbon tetrachloride, hydrocyanic acid gas, sulfur dioxide, carbon dioxide, chloropicrin,naphthalene, phosgene, amine, and cyanogen chloride. Numerous investigators have concluded that carbon tetrachloride is inefieotive' hydra cyanic acid as fails to kill weevils at any great depth 'elow the surface of thegrain; sul fur dioxide has low toxicity, is very inyurious to ironwork, destroys the germination power oil wheat, makes a sticky dough and hinders fermentation, the bread obtained being heavy and not lit for consumption; carbon diox de is efiective only in tightly-sealed containers and at relatively hi h concentrations over a considerable perio of time; the use of chloropicrin requires a gas mask and its low vapor pressure at ordinary temperafumigated flour before it is suitable for hairing; naphthalene is not very efiective and its odor is persistent and highly objectionable; phosgene is very poisonous to man andcornparatively non-poisonous to insects and its high vapor pressure makes it dificult to control; the toxicity of arsine to insects'is comparatively low; and the shortcomings of cyanogen chloride as a fumigant are essentially the same as those of hydrocyanic acid gas.

It is evident, therefore, that there is great need for a fumigant which is effective in ridding wheat and other cereals of injurious in.- sects, which is not dangerously toxic nor highly disagreeable to those handling the materail and which can be used, without danger of lire or explosion. 4

We have found that the esters of halogenated fatty acids are efiective insecticides; that they do not injure the milling and baking ualities of wheat; that they do not bleach or ot erwis'e injure'clothing and fabrics; that they do not corrode metals; and that they can be mixed with non-inflammable liquids such as carbon tetrachloride to form non-inflammable mixtures. I They thus are suitable for monochloroacetic, dichloroacetic, trichloroacetic, monobromoacetic, betachloropropionic, and alphaand beta-bromoproplomc acids are particularly suited for use as fumigants. While the esters of the brOmo-substi tuted acids are more toxic than the corresponding chloroones, the lower price of chlorine more than offsets this difierence in toxicity. We, therefore, prefer to use esters of the chloro-substituted fatty acids, and of these the esters of monochloroacetic acid are the best.

The following esters of monochloroacetic acid are particularly suited for, use as fumiants: methyl, eth l, isopropyl, normal butyl End secondary bullyl. These are all liquids at ordinary temperatures, possess leasant odors, are inexpensively prepared an can be made reasonabl free from fire hazard by v mixing with car on tetrachloride.

By the term freasonably free from fire hazard we mean a material whose vapor heated to 122 F. in admixture with air in a box or other rece tacle, and sparked with an electric spark, wi 1 not propagate a flame. A material which passes this test is considered to be free from fire hazard when used under ordinary conditions.

In place of carbon tetrachloride other chlorinated hydrocarbons may be used, such as trichloroethylene and tetrachloroethylene; or any other non-inflammable liquid such as halogen or nitre substituted compounds may be used, c. g., chloropicrin or tetranitromethane. a

On account of its cheapness and ready volatility we prefer to use carbon tetrachloride to make non-inflammable mixtures with the esters of halogenated fatty acids. Preferably, from 1 to 3 volumes of carbon tetrachloride should be added to each volume of the ester to make a non-inflammable mixture, but a mixture containing anywhere from to 10 per cent by volume of ester is otent as an insecticide and maybe employe The boiling points and formulas of these esters oi monochloroacetic acid, are as follows:

' menses exposure at a temperature of about 75 varies from about 1.5 ounds per 1,000 cubic r 'fcet of enclosed space or the methyl ester to about 6 pounds for the normal butyl ester.

The processes of applying these esters are exactly the same as those used with carbon disulfide. The mixtures may sprinkled, or sprayed over the surface of the grain it is desired to fumigate; the mixtures may be placed in shallow pans and allowed to evaporate; the mixtures, either in the form of a liquid or a va or, may be pumped into the grain at any desired depth through a pipe provided with orifices along its length or at its extremity.

While we have described the use of these" esters against weevils in wheat, their application as insecticides is not restricted to this purpose. These esters may be used intheform .of a spray to kill flies, mosquitoes and other household insects; or as a fumigant to kill any insect in an enclosed space, such asv insects on trees or other vegetation temporarily confined under a fumigating test; insects in clothing, carpets, furs, upholstered furniture, etc., in a fumigatin'g vault; insects in be poured,

drawers, closets, trunks, boxes, or rooms'that can be tightly closed; insects in mills, warehouses, ships, etc., and other laces where the va ors of the fumigant can confined for a de 'te-period of time.

Havingthus described our invention, we I claim:

1. As a new composition of matter a mixture of an ester of a halogenated fatty acid and a non-inflammable liquid, miscible therewith, in such proportion as to be non-inflammable at ordinary temperatures.

2. As a new composition of matter a. mixture of an ester of monochloroacetic acid and a non inflammable liquid miscible therewith, in such proportion that the vapor of the mixture, w with air, will not propagate a flame.

3. As a new composition of matter a mixture of 1m 9 volumes of an ester of monochloroacetic acid and 9 to 1 volumes of carbon tera'chloride. v

4. An insecticide containin as its essential active in redient an ester .0 a halogenated fatty Methyl monochloroacetate CH CIC OOCHQ 131.5 C.

Ethyl monochloroacetate CILCICOOC HB 144.2 Isopropyl monochloroacetate CH ClCOOGH8CHg'," 145 f Normal butyl monochloroacetate CH CICO C 9 175 These esters are all nearly insoluble in water, but readily soluble in ether, carbon tetrachloride, and other organic solvents.

The minimum lethal dose e of these esters acetic acid.

- 6. An insecticide, fungicide and disinfecten heated to 122 F'. in admixture 5 Aninsecticide containing as its essential active mgred1ent an ester of monochloroant comprising saturated aliphatic compounds containing the monochloroacetyl 65 to rice weevils in wheat, a owing 24 hours group.-

' 7. A11 insecticide, fungicide and disinfectant comprising saturated ali hatic esters containing the monochloroacety group.

8. An insecticidal fumigant containing as its essential active ingredient an ester of monochloroacetic acid.

9. As an insecticidal fumigant an ester of monochloroacctic acid.

. RURIC G. BOARK.

RICHARD T, COTTON. 

